Fuso V Queen Elizabeth

[dunmunro]

It seems obvious that if the shell ended up 2km away and they found it there, it didn't "burst". Can you come up with an explanation that makes sense?

When an AP shell "bursts" the base and nose of the shell usually remain intact, the base, with most of the weight of the shell is always very recognizable, as a picture of one of Hood's 15" shells inside Dunkerque, on page 47 of Allied BBs shows very clearly, with the lower 1/2 or so of the shell more or less intact. If Hood's shell burst on the Turret, it seems likely that the heavy base, for example, would end up some distance from Dunkerque, and even a few hundred FPS remaining SV would be sufficient to propel the remains of the shell that far.

[alecsandros]

I don't know if these results and those of the Richelieu tell us much about French armour. Certainly Richelieu's barbette armour seemed to do well.

They don't tell us much, indeed - there weren't enough real life penetrations for that. But they tell us something - that the French armour may have been of very poor quality. For further hints towards that conclusion, we should bear in mind also the damage received by 227kg bombs on the JB and the devastating torpedo damage suffered by the Richelieu (which is still controversial, I know).

Of course, we can't know for certain, but I hope we'll have some answers, from someone who researched or read about it more.

P.S.: Jean Bart's armour deflected 2 of the 406mm shells coming from Massachussets. The first glanced of Turret 1 (covered in 420mm of armor), the second glanced of barbette 2 (protected by 366mm of armor).

[tommy303]

When an AP shell "bursts" the base and nose of the shell usually remain intact, the base, with most of the weight of the shell is always very recognizable, as a picture of one of Hood's 15" shells inside Dunkerque, on page 47 of Allied BBs shows very clearly, with the lower 1/2 or so of the shell more or less intact.

Normally the shell body is pretty much completely shattered in a normal high order detonation. The area around the explosive cavity is converted into small to medium fragments with considerable anti-personnel effect, while the nose of an AP shell shatters into fewer, but larger fragments with high anti-material potential. The base plug is frequently blown free intact. What the photo in G&D shows is a 15-in shell which appears to have had a low order detonation which failed to completely destroy the shell. This was not an unusual occurance, as in 1941 the British were still using picric acid as an exploder in the gaine; sometimes it would initiate a high order detonation, sometimes not, and this erratic behavior led to development of improved gaines with more powerful boosters like tetryl. It is also possible the shell suffered sufficient damage to cause it to partially break up with damage reaching the explosive cavity.

[Dave Saxton]

The photo is very close to what we should expect from the descriptions (Krupp) of a shell that is broken up by axial forces as it begins to shift trajectory more toward the normal as the floor of the plate starts to break away.

The matter of the turret roof scoop is really not so mysterious if they used FH armour. Factoring in the slope of the turret roof with the angle of fall, and the impact velocity at that range: it should have penetrated intact about 155mm FH armour. The shell actually performed somewhat below what we should expect.

There exists evidence alluding to the poor quality of French homogenous armour in the historical literature. This is not new. It is specifically mentioned in MA6. Several years ago I ran across some metalurigical studies of French FM homgenous plates that found that its toughness and ductility had been compromized by sulfer inclusions. This of course only proves this for that lot of plates, but it does point to an impurities problem in the French manafacture.

[alecsandros]

The matter of the turret roof scoop is really not so mysterious if they used FH armour. Factoring in the slope of the turret roof with the angle of fall, and the impact velocity at that range: it should have penetrated intact about 155mm FH armour. The shell actually performed somewhat below what we should expect.

I ahve an issue here Dave: the turret roof for the Dunkerque was horizontal, so I don't see how it could add to the angle of fall. And speaking about angle of fall, at 14km the angle of fall should be 13.6 degrees, extremely difficult to believe it could penetrate 155mm of armor..

[Bgile]

The matter of the turret roof scoop is really not so mysterious if they used FH armour. Factoring in the slope of the turret roof with the angle of fall, and the impact velocity at that range: it should have penetrated intact about 155mm FH armour. The shell actually performed somewhat below what we should expect.

I ahve an issue here Dave: the turret roof for the Dunkerque was horizontal, so I don't see how it could add to the angle of fall. And speaking about angle of fall, at 14km the angle of fall should be 13.6 degrees, extremely difficult to believe it could penetrate 155mm of armor..

Yes, that kind of penetration seems completely beyond anything in the ballistics tables I've seen.

[Bgile]

It seems obvious that if the shell ended up 2km away and they found it there, it didn't "burst". Can you come up with an explanation that makes sense?

When an AP shell "bursts" the base and nose of the shell usually remain intact, the base, with most of the weight of the shell is always very recognizable, as a picture of one of Hood's 15" shells inside Dunkerque, on page 47 of Allied BBs shows very clearly, with the lower 1/2 or so of the shell more or less intact. If Hood's shell burst on the Turret, it seems likely that the heavy base, for example, would end up some distance from Dunkerque, and even a few hundred FPS remaining SV would be sufficient to propel the remains of the shell that far.

Any then they would have said "a number of small pieces of Hoods shell were found spread over a large area on shore".

Also, if it burst on impact that means the fuze delay failed completely. I just don't believe that's what happened.

[Dave Saxton]

I have an issue here Dave: the turret roof for the Dunkerque was horizontal, ..

According to drawings I have on hand it was not horizontal but sloped.

[Byron Angel]

I have an issue here Dave: the turret roof for the Dunkerque was horizontal, ..

According to drawings I have on hand it was not horizontal but sloped.

..... The long (about 3+ feet, according to the measuring reference in the photo) and very narrow slot and the absence of any >>visible<< lateral fragment scarring displayed by photos provided in G&D also suggest the possbility of the plate being opened up by the strike of a dud shell, with the shell mid-body breaking up on impact and the very heavy solid nose of the shell ricocheting and carrying on a considerable distance beyond.


Byron

[Terje Langoy]

Actually, Dave is correct... The larger portion of the turret roof of Dunkerque is slightly forward sloped. I´d suggest a 5+ deg forward angle, just to put a number on it.

[alecsandros]

I've watched again the drawings in G&D regarding the damage from the 2nd shell.

Dave, you are right about the sloping :) The shell struck the oblique portion of the turret, BUT the steeping angle is very small (5-7 deg?, which in conjuncture whith the falling angle of 13.6 would end up at 18.6-20.6 degrees) while the necessary penetration angle should be around ~30deg.

[Gary]

I dont think we can criticise Dunkerques armour too much because it was penetrated by Hood.
Dunkerque wasnt built to take on Battleships.

As Tommy pointed out, her intended prey would have been German Pocket Battleships or Italian cruisers.

However, somewhere along the line the French must have altered their plans as they upgraded the armour on Strasbourg

[yellowtail3]

...so how would those Brit shells done against Fuso's armor?

[dunmunro]

When an AP shell "bursts" the base and nose of the shell usually remain intact, the base, with most of the weight of the shell is always very recognizable, as a picture of one of Hood's 15" shells inside Dunkerque, on page 47 of Allied BBs shows very clearly, with the lower 1/2 or so of the shell more or less intact.

Normally the shell body is pretty much completely shattered in a normal high order detonation. The area around the explosive cavity is converted into small to medium fragments with considerable anti-personnel effect, while the nose of an AP shell shatters into fewer, but larger fragments with high anti-material potential. The base plug is frequently blown free intact. What the photo in G&D shows is a 15-in shell which appears to have had a low order detonation which failed to completely destroy the shell. This was not an unusual occurance, as in 1941 the British were still using picric acid as an exploder in the gaine; sometimes it would initiate a high order detonation, sometimes not, and this erratic behavior led to development of improved gaines with more powerful boosters like tetryl. It is also possible the shell suffered sufficient damage to cause it to partially break up with damage reaching the explosive cavity.

I dunno, it doesn't sound like a low order detonation:

"3rd 15" pierced 115mm deck, secondary ammunition handling room causing fires and detonation of two shells , passed through several splinter bulkheads, then detonated, in a fan room "totally" destroying that compartment, blast and fumes damage to forward engine room through airvents putting all machinery there out of action and killing 20 of 30 crew in the engine room.

4th 15" dived under the main belt and exploded on contact with the SPS armoured bulkhead, causing fires and severe damage to adjacent machinery spaces, leaving only one engine room in operation. 2nd Edit Note: Dunkerque had 6 boilers in 3 compartments and 4 shafts with two engine rooms. Her main machinery spaces did not have centre line bulkheads. G&D state that only the after engine room and one boiler room remained operational."

It must have been the 3rd hit, where the shell body was photographed.

[Dave Saxton]

I've watched again the drawings in G&D regarding the damage from the 2nd shell.

Dave, you are right about the sloping :) The shell struck the oblique portion of the turret, BUT the steeping angle is very small (5-7 deg?, which in conjuncture whith the falling angle of 13.6 would end up at 18.6-20.6 degrees) while the necessary penetration angle should be around ~30deg.

I may have mistakenly measured a greater slope. Double checking (and assuming my drawing is correct) it ends up about 24 * instead of about 27*. Remember this is FH armour instead of high quality homogenous armour (where the penetration would be much less in this type of impact). The penetration of FHA is between 160mm and 140mm for a shell that breaks up, which this shell did. Its about 130 for a shell that remains intact. Did the ship develop a slight list before this and the deck hit were received?